Rotary engine of trochoidal design

ABSTRACT

A rotary internal combustion engine of trochoidal type having phasing gearing between the housing and the rotor, wherein the large gear borne by the rotor and the smaller gear borne by a side wall and through which the shaft passes, are in engagement by means of teeth extending axially from their end faces. This arrangement permits the use of gears of smaller outer diameter, hence allowing more space on the rotor side face for seals, a larger and stronger shaft passing through the small gear, and stronger gear teeth.

- in] 3,801,240 Apr. 2, 1974 United States Patent [1 1 Rut 3,655,3024/1972 Hermes et 418/61 A ROTARY ENGINE 0F TROCIIOIDAL DESIGN [75]Inventor:

Max Ruf, Obereisesheim, Germany Primary Examiner c J. Husar Assignees:Audi NSU Auto Union Assistant Examiner- Leonard SmithAktiengesellschaft, Neckarsulm; Attorney, Agent, or Firm-Raymond P.Wallace Wankel G.m.b.H., Lindau,

Bodensee, both of Germany Apr. 6, 1973 ABSTRACT [22] Filed:

[21] Appl. No; 348,715

[30] Foreign Application Priority Data May 9, 1972 the rotor, whereinthe large gear borne by the rotor Germany..........;... 2222568 and thesmaller gear borne by a side wall and through which the shaft passes,are in engagement by means of teeth extending axially from their endfaces. This arrangement permits the use of gears of smaller outerdiameter, hence allowing more space on the rotor side face for seals, alarger I and stronger shaft passing References Cited through the smallgear, and stronger gear teeth. UNITED STATES PATENTS 6 Claims, 3 DrawingFigures 3,400,604 Jones 418/61 A ROTARY ENGINE OF TROCHOIDAL DESIGNBACKGROUND OF THE INVENTION This invention relates to a rotary pistonengine of trochoidal design as shown generally in U. S. Pat. Nos.2,988,008 and 2,988,065, wherein a rotor is disposed within the enginecavity of a multilobed trochoidal peripheral housing, the rotor beingrotatably mounted on an eccentric portion of a shaft transpiercing theside walls of the housing. The rotor bears on one side face a gearcoaxial with the rotors axis of rotation on the eccentric, and inengagement with a smaller gear borne by a housing side wall. The smallergear is coaxial with the shaft axis, and the shaft passes through thesmaller gear. These gears assist in maintaining the selected rotationalphasing between the rotor and the shaft.

In such engines of the prior art the phasing gears have been spur gearswith radially extending teeth, the smaller gear being of pinion typewith an annular web portion from which the teeth extend radiallyoutwardly, and the large gear being a ring gear having an annular webwith the teeth extending radially inwardly therefrom. Such gears areexemplified in U. S. Pat. Nos. 3,091,386 and 3,323,497. The annular webmembers of both gears have been used to provide attachment to theirrespective supporting means. The necessary radial width of the webmember of the ring gear limits the amount of space available on therotor side face for positioning the annular oil seals surrounding thegear, as shown in U. S. Pat. Nos. 3,171,590 and 3,400,939.

The radial width of the web of the pinion gear limits the diameter ofthe shaft passing therethrough, this gear being required to be insuitable ratio to the ring gear. ln order to keep the shaft diameter aslarge as possible, use has been made of gear teeth having a relativelysmall module, usually about 1.5, the module being defined as the pitchdiameter of the gear in millimeters divided by the number of teeth. Asmall module necessitates a relatively large number of relatively weakteeth. The restricted space on the rotor face results in structurallimitations in the possible ratio of e:R of the engine, where e is thespacing between the parallel axes of rotation of the rotor and of theshaft, and R is the radius from the rotational axis of the rotor to arotor apex.

SUMMARY rotary engine with phasing gearing which enables the use of alarger diameter shaft.

It is another object to provide such an engine with phasing gearingleaving a larger clear area of the rotor side face available for sealinstallation.

It is another object to provide a rotary engine with such gearing havingstronger teeth which can be more economically produced.

Still another object is to provide gears on parallel shafts havingmeshing end-face teeth.

A further object is to provide a rotary engine having phasing gearingwith a larger module than was possible in the prior art.

These objects and advantages and others ancillary thereto will bereadily understood on reading the following specification in connectionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an axial cross-section inelevation of a trochoidal rotary engine embodying the phasing gearing ofthe invention;

FIG. 2 is an exploded perspective view showing schematically the phasinggears of FIG. 1 in their relation to the rotor; and 5 FIG. 3 is afragmentary view of portions of the rotor and a side wall, showing amodified embodiment of the phasing gearing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention will be describedin connection with a rotary engine having a basically epitrochoidalperipheral housing of two lobes. and an arcuately triangular rotorhaving three apexes. However, it is to be understood that the inventionis also applicable to such trochoidal engines of other design, such asone with a three-lobed housing and-a four-apexed rotor, or a onelobedhousing and a two-apexed rotor, or to any mechanism in which phasinggearing is provided between a rotor and a housing.

'In FIG. 1 there is shown a rotary engine having a housing comprising aperipheral shell 1 with a twolobed trochoidal inner surface 2, and twoside parts '3 and 4, defining an engine cavity. A rotatable shaft 5extends through the side parts 3 and 4, being appropriately mounted inbearings borne by the side parts, and having an eccentric portion 6disposed within the engine cavity. A generally triangular rotor 7 isrotatably mounted on the eccentric 6, the rotor bearing at its apexesseal members 8 which during rotation of the rotor continuously sweep theinner peripheral'surface 2 in sealing relation therewith. The axis 11 ofrotation of the rotor on the eccentric portion is displaced from, butparallel to, the rotational axis 12 of the shaft.

The shaft rotates at three times the speed of the rotation of the rotorwithin the housing. This speed ratio is maintained by synchronizedphasing gearing comprising a ring gear 9 mounted on a side face of therotor and in mesh with a pinion gear 10 borne by the adjacent side partof the housing. Although the gears are referred to as ring and piniongears, it is to be understood that they are not the known examples ofgears bearing those designations, wherein a ring gear would have teethprojecting in the radially inward direction and the pinion gear wouldhave teeth projecting in the radially outward direction. Theconfiguration of the present ring and pinion gears will be describedbelow.

ring gear 9 has the same outer and inner diameters as the outer andinner'diameters of the teeth 13 extending therefrom, and gear base 16 ofthe pinion gear 10 has the same outer and inner diameters as the outerand inner diamters of its axially extending teeth, with the pitchdiameters of the two gearsbeing tangent at the point of completemeshing.

In the embodiment shown in FIGS. 1 and 2 the teeth 13 and 14 of the twogears are attached at one end exclusively to the gear bases 15 and 16respectively, the opposite ends of the teeth-being free-standing, asbest shown in FIG. 2. The individual teeth are thus self supporting, andit is possible to produce or machine their form and engaging surfaces bya rotating end mill or a rotating pot-shaped grinding wheel. The toothflanks may advantageously be designed on an involute approximating acircular are, for the purpose of making it possible to produce them bymeans of a rotating tool with the greatest possible accuracy. However,it is also possible to produce the gears by a sintering process. Also,the teeth can of course be cut by any of the known gear-cutting means.Although the tooth form is shown only schematically in FIG. 2, it is tobe understood that'the teeth may have any form which would be suitablefor radial teeth of the prior art.

Because the-radial breadth of the gears 9 and 10 is determined solely bythe radial height of the teeth 13 and 14, this produces substantialadvantages in comparisonwith the gears of the prior art, the radialextent of which was the sum of the tooth height plus the radial width ofthe flange or web. With the same radial extent as in a prior art gear,the gears of the invention can have a module two or three times that ofthe ordinary teeth, and thus teeth that are'two or three timesstronger.,

On the other hand, if there is used with the invention the module ofordinary teeth, 1.5 for example, then the radial extent of the gears issubstantially reduced. With the pinion this reducton in radial breadthis taken from the inner diameter, so that it is feasible to have alarger aperture therethrough for the passage of a shaft of greaterdiameter and higher strength. In the case. of the ring gear thereduction of radial breadth results in a smaller outer diameter, so thatin engines having a great angle of traverse, that is, a small e.'Rratio, there remains sufficient room on the side face of the rotor for g4 insure centering. g

In the example already described the gear teeth are connected to theirrespective gear bases only at one end. The embodiment shown in FIG. 3differs in that each gear base 15' and 16 is provided with an annularextension 20 and 21 respectively, which in addition to the endconnection of the teeth also connect what would be the roots of theteeth in ordinary spur type gears. That is, the axial extension 20 ofthe ring gear is a thin barrel disposed on the radially outward or rootside of the teeth 13' and connected thereto, and the extension 21 of thepinion is a thin barrel disposed on the radially inward or root side ofthe teeth 14' and connected thereto. Theseextensions 20 and 21 give verysubstantial strength to the teeth 13 and 14', even when the barrels arevery thin, since the teeth are now unitary on two sides with the gearbases. The total radial breadth of the gears 9' and 10' is onlyimmaterially increased by these extensions.

In this embodiment, although the gears may be mounted in the mannerpreviously described, they may also be advantageously mounted by heavydowels 22 between the ring gear 9 and rotor 7, and by similar dowels 23between the pinion l0 and the side wall 3, the dowels beingpressed intocorresponding holes in the gears and their respective mounting members.

' Gears 9' and 10' are preferably fabricated by a sintering process.

What is claimedis:

1. In a rotary engine of trochoidal type having a housing comprisingside walls and a peripheral wall defining an engine cavity, a shafttranspiercing the side walls and having an eccentric portion disposedwithin the cavity, a rotor rotatably mountedon the eccentric and bearingon one side face a gear in engagement with a gear borne by the adjacentside wall, the improvement comprising: each of the gears having a gearbase portion with gear teeth extending axially therefrom.

2. The combination recited in claim 1, wherein the roots of the teeth ofeach gear are connected to one another by annular extensions of theirrespective gear bases.

3. The combination recited in claim 1, wherein the flanks of the profileof the teeth of each gear are on circular arcs approximating involutetoothing.

4. The 'combinationrrecited in claim 1, wherein the gears are formed ofsintered material.

5. The combination recited in claim 1, wherein the teeth of each gearare connected ecclusively at one end of the gear teeth to theirrespective gear bases.

6. The combination recited in claim 5, wherein the inner and outerdiameters of the teeth of each gear are substantially equal to therespective inner and outer diameters of their respective gear bases.

1. In a rotary engine of trochoidal type having a housing coMprisingside walls and a peripheral wall defining an engine cavity, a shafttranspiercing the side walls and having an eccentric portion disposedwithin the cavity, a rotor rotatably mounted on the eccentric andbearing on one side face a gear in engagement with a gear borne by theadjacent side wall, the improvement comprising: each of the gears havinga gear base portion with gear teeth extending axially therefrom.
 2. Thecombination recited in claim 1, wherein the roots of the teeth of eachgear are connected to one another by annular extensions of theirrespective gear bases.
 3. The combination recited in claim 1, whereinthe flanks of the profile of the teeth of each gear are on circular arcsapproximating involute toothing.
 4. The combination recited in claim 1,wherein the gears are formed of sintered material.
 5. The combinationrecited in claim 1, wherein the teeth of each gear are connectedecclusively at one end of the gear teeth to their respective gear bases.6. The combination recited in claim 5, wherein the inner and outerdiameters of the teeth of each gear are substantially equal to therespective inner and outer diameters of their respective gear bases.